docs: def list(self, subid, params=None):
          ''' /v1/server/list_ipv4
          GET - account
          List the IPv4 information of a virtual machine. IP information is only
          available for virtual machines in the "active" state.
  
          Link: https://www.vultr.com/api/#server_list_ipv4
          '''
          params = update_params(params, {'SUBID': subid})
          return self.request('/v1/server/list_ipv4', params, 'GET')